Why the 51 is so slow and unreliable

12 Mar

As I mentioned on Sunday, this week AC Transit is holding several open houses to discuss proposed changes to the 51 line. And as promised, I’ve pored over the long report they prepared so I could break down the most interesting parts to share here.

First though, I just wanted to say that the open house I attended on Monday in Berkeley was extremely well organized and effective. ACT staff managed to condense an 86 page report into a 15 minute presentation that covered almost all of the important facets of the report. More importantly, they explained complex issues in a way that made sense to the audience. Though there were some Van Hool and BRT haters in the crowd, most people gave constructive feedback and seemed to appreciate the event and the work that ACT had put into this report. So good work ACT, and thanks!

I’m going to break the report into two posts. This post will discuss the reasons that the 51 is so damn slow and unreliable, and the next post will discuss some of ACT’s ideas for improving the line.

So how slow is the 51? Here are some interesting statistics from the report:

  • The 51 only spends 50% of its time actually moving, while 20% is spent in dwell time (stopped at a bus stop) and 30% is spent in delays (i.e. stuck in traffic).
  • When the 51 is moving, it’s traveling slowly. On average, it moves at 9 miles per hour, 25% slower than the average for ACT buses.
  • The 51 is incredibly unreliable. All of the major stops, both northbound and southbound were rated as D, E, or F for level of service, which ranges from irregular headways with some bunching to most vehicles being bunched.


Bus stop spacing: If you’ve ridden the 51, I’m sure you’ve noticed that the bus stops are incredibly close together. It seems that every time I take it down Broadway, we stop at every block, which of course takes forever and makes me crazy. According to ACT, the ideal amount of space between bus stops is 800-1300 feet, yet on the 51 line, 87 bus stops (more than half of the stops) are less than 800 feet from the next stop. This slows the whole route down because pulling over, picking up passengers, and getting back into traffic at all of these stops takes a long time.

Bus stop placement: The best placement for bus stops is generally at the far side of a signalized intersection, because this allows buses to make it through the light before stopping. Yet on the 51 line, 60% of the stops are not at this preferred location. This means that buses often get stuck behind the light or even wait through two or more signals to get through the intersection. This factor is extremely important, especially since ACT’s study indicates that 80% of delay time is caused by traffic signals.

Traffic: Unsurprisingly, traffic leads to delays on the 51. Specifically, this has the greatest effect when buses are reentering traffic or being obstructed by turning traffic. And it’s not just automobile traffic that lead to the delays – yielding to bicyclists and pedestrians causes 4% of the overall delay.

Parking: Automobiles waiting for street parking spots and pulling into them delay the 51. Also, automobiles parked in bus zones cause traffic, as buses must wait for them to pull out.


Fare payment: This accounts for a significant amount of dwell time and can be highly variable. Interestingly, it was found that passes that have to be dipped into the box (i.e. 10 ride passes, 31 day passes) took the longest at 6.22 seconds, while cash payment came in a close second at 5.59 seconds. Flash pass payments (like the UC Berkeley class pass) were by far the most quick, at 2 seconds.

Crowded buses: Packed buses are not only uncomfortable, but they cause longer dwell time. Especially when riders are standing towards the front of the bus, this can greatly slow down boarding.

Front door alighting: When riders exit the bus through the front door, this delays riders from boarding the bus. On average, each person alighting from the front of the bus causes a 2 second delay.

Senior or disabled boarding: This unsurprisingly causes additional dwell time. Fortunately, the Van Hool buses seem to make wheelchair (and stroller) boarding quicker, though that was not discussed in this study.

Door opening twice: It didn’t surprise me that this added to dwell time, but what surprised me was how much time it added. Every time the doors are closed and then opened again, this adds nearly 14 seconds to dwell time! That’s the same amount of time it would take 7 passengers to board using a flash pass.

So now you know why the 51 is so slow and unreliable. Check back tomorrow for AC Transit’s proposed solutions to these problems.

4 Responses to “Why the 51 is so slow and unreliable”

  1. Hayden March 14, 2009 at 11:27 am #

    I wonder if there was a discussion about which problem is relatively more important?

    That is, for me, speed doesn’t matter as much as regularity of headway. If the drivers were in communication with each other, periodically pulled over and waited if they caught up with another bus, or took other measures to avoid bus bunching–so that the 51 came every 8-12 minutes at peak times, instead of a bunch of buses every 30-45 minutes, that would make a big difference.

    It would be nice if the bus was able to go faster, but all things considered, I’d prefer being on the bus going to my destination, as opposed to waiting at the stop wondering why a 51 hasn’t come by in mydirection in the last half hour at peak times.

    • Becks March 14, 2009 at 6:28 pm #

      Reliability certainly is the biggest problem, and I think AC Transit staff realize that. In the next post (which I had hoped to write yesterday but haven’t found the time), I’ll lay out there recommendations for improving both reliability and speed.

  2. JHorner March 16, 2009 at 3:53 pm #

    This is awesome. That’s all I have to say. Well done

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